Field of the Invention
The present invention relates generally to diagnostic assays for analytes in a fluid sample. In particular, the invention relates to devices and methods for detecting an analyte in a bodily fluid.
Description of the Related Art
Detection of human chorionic gonadotropin (hCG) in urine samples is routinely used to determine a woman's pregnant/non-pregnant status. Traditional one-step pregnancy test devices detect hCG by utilizing a double antibody system in a lateral flow format resulting in a “sandwich” complex of hCG, a capture antibody and a labeled antibody, which is captured at a specific detection area on a test strip. A digital version of the pregnancy test device consists of an opto-electronic reader powered by an internal battery that measures the absorbance/reflectance of the label particles specifically captured at the detection area of the test strip and automatically subtracts any non-specific background color from an adjacent area of the test strip that is outside the detection area. The adjusted measurement of absorbance/reflectance of accumulated label particles at the detection area is processed to generate a detection determination for display as a clearly read YES+/PREGNANT or NO−/NOT PREGNANT digital result on a liquid crystal display (LCD) screen.
Although electronic readers provide the added convenience of eliminating the end-user step of interpreting the results of the test, a step required in traditional lateral flow devices, there is room for improvements.